Auto-document feeder and image reading apparatus

ABSTRACT

An auto-document feeder includes: a paper feeding section configured to feed original documents one by one; a first feeding section configured to feed the fed original document through a first feeding path; a second feeding section configured to feed the fed original document through a second feeding path; a third feeding section configured to alternately nip one by one the fed original documents; a determining section configured to determine that the original document is nipped by the third feeding section; and a document diverting and feeding section configured to alternately divert and feed, into the first feeding path and the second feeding path, the fed original documents and, if the preceding original document is present, after the preceding original document is detected by the determining section, feed the following original document into the first or second feeding path into which the preceding original document is not fed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from U.S. provisional application 61/393335, filed on Oct. 14, 2010 and Japanese Patent Application No. 2011-214558 field on Sep. 29, 2011; the entire contents all of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an auto-document feeder and an image reading apparatus that are used in a copying machine, a printer, and the like and automatically feed an original document and read a document image.

BACKGROUND

In an auto-document feeder and an image reading apparatus including an image reading section such as a scanner used in an image forming apparatus such as a copying machine or a printer, an increase in image reading speed is desired. As an image reading apparatus that increases reading speed for a document image, there is known, as a related art, an image reading apparatus that includes a first feeding path for feeding an original document to an image reading section and a second feeding path different from the first feeding path and, in continuously feeding plural original documents and reading images of the original documents, alternately diverts the original documents to the first and second feeding paths to feed the original documents.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic diagram of an image reading apparatus according to an embodiment;

FIG. 2 is a block diagram of a control system for an ADF according to the embodiment;

FIG. 3 is a flowchart for explaining processing from power-on until the start of feeding of an original document in the embodiment;

FIG. 4 is a flowchart for explaining processing from the start of feeding of the original document until feeding of the original document to an OUT feeding section in the embodiment;

FIG. 5 is a flowchart for explaining feeding of the original document using the OUT feeding section in the embodiment;

FIG. 6 is a flowchart for explaining processing from the start of reading of an image until the end of the reading in the embodiment;

FIG. 7 is a flowchart for explaining of feeding of a following original document using an IN feeding section in the embodiment;

FIG. 8 is a flowchart for explaining completion of feeding in the embodiment;

FIG. 9 is a diagram for explaining the start of feeding of a first original document in the embodiment;

FIG.. 10 is a diagram for explaining feeding of the first original document to the OUT feeding section in the embodiment;

FIG. 11 is a diagram for explaining standby of the first original document in the OUT feeding section in the embodiment;

FIG. 12 is a diagram for explaining the start of feeding of a second original document in the embodiment;

FIG. 13 is a diagram for explaining feeding of the second original document to the IN feeding section in the embodiment;

FIG. 14 is a diagram for explaining feeding of the second original document following the first original document in the embodiment;

FIG. 15 is a diagram for explaining a distance between the first and second original documents in the embodiment;

FIG. 16 is a diagram for explaining the start of feeding of a third original document in the embodiment; and

FIG. 17 is a diagram for explaining feeding of the third original document to the OUT feeding section in the embodiment.

DETAILED DESCRIPTION

According to an embodiment, an auto-document feeder includes a paper feeding section configured to feed individually original documents or in one by one manner, from which images are read by an image reading section.

A first feeding section configured to feed the original document, which is fed by the paper feeding section, in a direction of the image reading section through a first feeding path. A second feeding section configured to feed the original document, which is fed by the paper feeding section, in the direction of the image reading section through a second feeding path different from the first feeding path. A third feeding section configured to alternately nip one by one the original documents fed by the first feeding section and the second feeding section and feed the original documents to the image reading section. A determining section configured to determine that the original document is nipped by the third feeding section. A document diverting and feeding section configured to alternately divert and feed the original documents, which are fed by the paper feeding section, into the first feeding path and the second feeding path and, if a preceding original document is present, after the preceding original document is detected by the determining section, feed a following original document into the first or second feeding path into which the preceding original document is not fed.

An auto-document feeder and an image reading apparatus according to an embodiment are explained with reference to the accompanying drawings.

FIG. 1 is a diagram of an image reading apparatus 100 according to the embodiment. The image reading apparatus 100 includes a scanner 110, which is a first image reading section, and an auto-document feeder (ADF) 10 configured to feed an original document G to the scanner 110. The scanner 110 includes a READ document glass 110 a, a platen glass 110 b serving as a document placing table, and an optical mechanism 110 c. The optical mechanism 110 c optically reads an image of the original document G traveling on the READ document glass 110 a. Alternatively, the optical mechanism 110 c is moved by not-shown driving means in an arrow A direction (see FIG. 1) along the platen glass 110 b and optically reads an image of the original document G placed on the platen glass 110 b. The scanner 110 includes a photosensor such as a CCD (Charge Coupled Device) 110 d configured to photoelectrically convert a light signal from the optical mechanism 110 c into an electric signal. The auto-document feeder 10 is openably and closably attached to the scanner 110 by a not-shown hinge section. In an open state, the auto-document feeder 10 exposes the READ document glass 110 a and the platen glass 110 b. In a closed state (a state shown in FIG. 1), the auto-document feeder 10 covers the READ document glass 110 a and the platen glass 110 b. The auto-document feeder 10 continuously feeds original documents G to the READ document glass 110 a. The auto-document feeder 10 includes a paper feeding section configured to feed one by one the original documents G, from which images are read by the scanner 110, a first feeding section configured to feed the original document G, which is fed by the paper feeding section, in the direction of the READ document glass 110 a of the scanner 110 through a first feeding path. A second feeding section configured to feed the original document G, which is fed by the paper feeding section, in the direction of the READ document glass 110 a of the scanner 110 through a second feeding path different from the first feeding path. A third feeding section configured to alternately nip one by one the original documents G fed by the first feeding section and the second feeding section and feed the original documents G to the READ document glass 110 a of the scanner 110. And a document diverting and feeding section configured to alternately divert and feed the original documents G, which are fed by the paper feeding section, into the first feeding path and the second feeding path. The paper feeding section includes a document tray 11 on which the original documents G are stacked and placed, a pickup roller 12 configured to pick up the original documents G from the document tray 11, and separating and feeding rollers 13 configured to separate and feed the original documents G one by one in order to prevent double-feeding of the original documents G. The first feeding section includes, as the first feeding path, an OUT path 16 reaching from registration rollers 14 explained later to the READ document glass 110 a and includes, as first intermediate feeding rollers, intermediate OUT rollers 18 provided along the OUT path 16. The second feeding section includes, as the second feeding path, an IN path 17 reaching from the registration rollers 14 to the scanner 110 and includes, as second intermediate feeding rollers, intermediate IN rollers 28 provided along the IN path 17. The third feeding section includes pre-reading rollers 50 configured to feed the original document G, which passes through the OUT path 16 or the IN path 17, to the READ document glass 110 a of the scanner 110. Feeding path length of the OUT path 16 (a distance from the registration rollers 14 to the pre-reading rollers 50 through the OUT path 16) and feeding path length of the IN path 17 (a distance from the registration rollers 14 to the pre-reading rollers 50 through the IN path 17) are the length of a most frequently used sheet, for example, the length of a letter-size sheet (216 mm). Therefore, if an original document having a size equal to or smaller than the letter side is fed, during the feeding, the original document fits in the OUT path 16 and the IN path 17. The document diverting and feeding section is provided on a downstream side of the separating and feeding rollers 13 and includes the registration rollers 14 configured to align leading ends of the documents G and a gate 40 configured to divert the original documents G, which are fed by the registration rollers 14, to the OUT path 16 or the IN path 17.

The auto-document feeder 10 further includes post-reading rollers 51, pre-paper discharge rollers 52, paper discharge rollers 53, and a paper discharge tray 56 for discharging the original document G from the READ document glass 110 a. The post-reading rollers 51, the pre-paper discharge rollers 52, and the paper discharge rollers 53 constitute a paper discharge section. A contact image sensor (CIS) 60, which is a second image reading section, is provided between the post-reading rollers 51 and the pre-paper discharge rollers 52. The contact image sensor (CIS) 60 can be provided in, for example, a feeding path reaching from the pre-paper discharge rollers 52 to the paper discharge rollers 53.

The scanner 110 reads, on the READ document glass 110 a, an image on a front surface, which is a first surface, of the original document G traveling on a glass surface. The CIS 60 reads an image on a rear surface, which is a second surface, of the original document G traveling on the glass surface. Such a configuration makes it possible to advantageously read the images on both the surfaces of the original document G by performing document pass once.

An empty sensor 70 configured to detect presence or absence of the original document G is arranged above the document tray 11. A registration sensor 71 configured to detect that the original document G reaches the registration rollers 14 is arranged between the separating and feeding rollers 13 and the registration rollers 14. In the OUT path 16, a paper timing sensor OUT 72, which is a first timing sensor, configured to detect driving timing for the registration rollers 14 and the intermediate OUT rollers 18 are arranged. In the IN path 17, a paper timing sensor IN 73, which is a second timing sensor, is configured to detect driving timing for the registration rollers 14 and the intermediate IN rollers 28 are arranged. An ADF opening and closing detection sensor 90 configured to detect opening and closing of the auto-document feeder 10 is arranged in an upper part of the scanner 110.

A pre-reading sensor 76 is arranged between the pre-reading rollers 50 and the READ document glass 110 a. A reading sensor 77 is arranged between the post-reading rollers 51 and the pre-paper discharge rollers 52. A paper discharge sensor 78 is arranged between the pre-paper discharge rollers 52 and the paper discharge rollers 53. For example, in operation the empty sensor 70 is turned on if the original document G is present and is turned off if the original document G is absent to thereby detect presence or absence of the original document G. The sensors 71, 72, 73, 76, and 78 are turned on if the original document G reaches sensor positions and are turned off if the original document G passes the sensor positions to thereby detect the original document G.

The ADF opening and closing detection sensor 90 is turned on if the ADF 10 is in the open state and is turned off if the ADF 10 is in the closed state to thereby detect opening and closing of the ADF 10.

If a paper feeding motor 80 is turned on, the paper feeding motor 80 drives to rotate the pickup roller 12 and the separating and feeding rollers 13. If the paper feeding motor 80 is turned off, the paper feeding motor 80 stops the driving and rotation of the pickup roller 12 and the separating and feeding rollers 13. A pickup solenoid 81 is turned on and off to swing the pickup roller 12. If a registration motor (RGT motor) 82 is turned on, the registration motor 82 drives to rotate the registration rollers 14. If the registration motor 82 is turned off, the registration motor 82 stops the driving and rotation of the registration rollers 14. A gate solenoid 83 switches the gate 40 between different pivot positions. If the gate solenoid 83 is turned off, the gate 40 pivots in an arrow x direction and diverts the original document G to an OUT feeding section 26. If the gate solenoid 83 is turned on, the gate 40 pivots in an arrow y direction and diverts the original document G to an IN feeding section 27.

If an intermediate OUT motor 84 is turned on, the intermediate OUT motor 84 drives to rotate the intermediate OUT rollers 18. If the intermediate OUT motor 84 is turned off, the intermediate OUT motor 84 stops the driving and rotation of the intermediate OUT rollers 18. If an intermediate IN motor 86 is turned on, the intermediate IN motor 86 drives to rotate the intermediate IN rollers 28. If the intermediate IN motor 86 is turned off, the intermediate IN motor 86 stops the driving and rotation of the intermediate IN rollers 28. If a READ motor 87 is turned on, the READ motor 87 drives to rotate the pre-reading rollers 50, the post-reading rollers 51, and the pre-paper discharge rollers 52. If the Read motor 87 is turned off, the READ motor 87 stops the driving and rotation of the pre-reading rollers 50, the post-reading rollers 51, and the pre-paper discharge rollers 52. If a paper discharge motor 88 is turned on, the paper discharge motor 88 drives to rotate the paper discharge rollers 53. If the paper discharge motor 88 is turned off, the paper discharge motor 88 stops the driving and rotation of the paper discharge rollers 53.

A block diagram of a control system 120 mainly for controlling the ADF 10 is shown in FIG. 2. A main body control section 121 configured to control an entire image forming apparatus including the image reading apparatus 100 is connected to the photosensor/CCD 110 d and the CIS 60 of the scanner 110. The main body control section 121 controls a CPU 130 of the ADF 10 via an input and output interface 122. The empty sensor 70, the registration sensor 71, the paper timing sensor OUT 72, the paper timing sensor IN 73, the pre-reading sensor 76, the reading sensor 77, the paper discharge sensor 78, and the ADF opening and closing detection sensor 90 are connected to an input side of the CPU 130.

The pickup solenoid 81, the paper feeding motor 80, the RGT motor 82, the gate solenoid 83, the intermediate OUT motor 84, the intermediate IN motor 86, the READ motor 87, and the paper discharge motor 88 are connected to an output side of the CPU 130. The CPU 130 includes a timer function and controls to drive the motors and the solenoids on the basis of a timing result of the timer and detection results of the sensors. The CPU 130 executes, in conjunction with the main body control section 121, a control process for feeding an original document and reading a document image. According to the configuration explained above, the gate 40 and the registration rollers 14 cooperate with each other to alternately divert and feed the original documents G, which are continuously fed, into the OUT path 16 and the IN path 17. In diverting and feeding the original documents G, at a timing when the preceding original document G is nipped by the pre-reading rollers 50, i.e., if the pre-reading sensor 76 is turned on, the registration rollers 14 rotate and feed the following original document G into the OUT path 16 or the IN path 17 into which the preceding original document G is not fed. Therefore, if the original documents G having a size equal to or smaller than the letter size are continuously fed, in some cases, the preceding original document G and the following original document G are respectively present in the OUT path 16 and the IN path 17. However, the preceding original document G is typically nipped by the pre-reading rollers 50. Therefore, even if a jam of the original documents G occurs and the original documents G remaining in the OUT path 16 and the IN path 17 are removed, it is possible to easily discriminate which of the original documents G is the preceding original document G or the following original document G and easily perform a jam treatment. The intermediate IN rollers 28 and the intermediate OUT rollers 18 efficiently continuously feed the original documents G to the scanner 110 in a state in which a distance between a trailing end of the preceding original document G present in one of the OUT path 16 and the IN path 17 and a leading end of the following original document G present in the other path is reduced to nearly 0 mm. Therefore, the scanner 110 operating according to a control process of the main body control section 121 can read images of the original documents G at high speed.

A control process for continuously feeding the original documents G and reading images is explained in detail with reference to flowcharts of FIGS. 3 to 8. First, a control process for feeding a first original document G1 is explained. If a not-shown power supply for a main body apparatus is turned on, in ACT 200, the CPU 130 waits for the opening and closing sensor 90 of the ADF 10 to be turned on. If the opening and closing sensor 90 of the ADF 10 detects the closed state of the ADF 10 and is turned on, the CPU 130 confirms, on the basis of the fact that the opening and closing sensor 90 is on, that the ADF 10 is closed. Subsequently, in ACT 201, the CPU 130 checks whether all the sensors 71, 72, 73, 76, 77, and 78 in the feeding paths are off. The CPU 130 confirms that all the sensors 71, 72, 73, 76, 77, and 78 in the feeding paths are off and determines that the original document G is absent in all the feeding paths of the ADF 10. In ACT 202, the CPU 130 waits for the empty sensor 70 to be turned on. If the original document G1 is placed on the document tray 11 by the user, the empty sensor 70 detects the original document G1 and is turned on. The CPU 130 sends, on the basis of the fact that the empty sensor 70 is on, a document ON signal to the main body control section 121. Thereafter, in ACT 203, the CPU 130 waits for reception of a paper feeding request signal from the main body control section 121.

If the CPU 130 confirms in ACT 201 that any one of all the sensors is on, the CPU 130 determines that the original document G1 is present in the feeding paths and informs, using a not-shown display unit or the like, that a jam occurs.

If the CPU 130 receives the paper feeding request signal from the main body control section 121 in ACT 203, in ACT 206, the CPU 130 turns on the pickup solenoid 81, turns on the paper feeding motor 80, rotates the pickup roller 12 and the separating and feeding rollers 13, and starts a paper feeding operation for the original document G1. Subsequently, in ACT 207, the CPU 130 waits for the registration sensor 71 to be turned on. If the registration sensor 71 detects the original document G1 and is turned on, in ACT 208, the CPU 130 turns off the paper feeding motor 80 and turns off the gate solenoid 83 in a fixed time after the registration sensor 71 is turned on. After being fed for a fixed time according to the rotation of the pickup roller 12 and the separating and feeding rollers 13, the original document G1 collides with the registration rollers 14 and stops with a leading end position thereof aligned as shown in FIG. 9. The gate solenoid 83 is turned off to thereby set the gate 40 in a direction in which the original document G is diverted to the OUT feeding section 26. If the registration sensor 71 is not turned off even if the fixed time elapses in ACT 210, the CPU 130 determines that the document G causes a jam and informs the occurrence of the jam using the not-shown display unit or the like.

In ACT 211, the CPU 130 waits for a fixed time to elapse. If the fixed time elapses, in ACT 212, the CPU 130 determines whether the document G1 is an odd number-th original document. In this case, since the original document G1 is the first document, the CPU 130 determines that the original document G1 is the odd number-th original document. If the CPU 130 determines that the original document G1 is the odd number-th original document, in ACT 265, the CPU 130 checks whether the pre-reading sensor 76 is turned on by the preceding original document G. If the pre-reading sensor 76 is turned on, the CPU 130 proceeds to ACT 214. However, if the original document G1 is the first document (the preceding original document G is absent), the CPU 130 proceeds to ACT 214 without performing the check in ACT 265. In ACT 214, the CPU 130 turns on the RGT motor 82 and the intermediate OUT motor 84 and rotates the registration rollers 14 and the intermediate OUT rollers 18 at equal speed. As shown in FIG. 10, the original document G1 is diverted to the gate 40 and travels to the OUT feeding section 26.

In ACT 215 and ACT 217, the CPU 130 waits for, for a fixed time, the paper timing sensor OUT 72 to be turned on. If the paper timing sensor OUT 72 is turned on, in ACT 216, the CPU 130 turns off the RGT motor 82 and the intermediate OUT motor 84 and stops the rotation of the motors in a fixed time after the paper timing sensor OUT 72 is turned on. As shown in FIG. 11, the original document G1 stops before the pre-reading rollers 50. If the paper timing sensor OUT 72 is not turned on even if the fixed time elapses in ACT 215 and ACT 217, the CPU 130 determines that a jam of the original document G occurs and informs the occurrence of the jam using the not-shown display unit or the like.

In ACT 218, the CPU 130 waits for a feeding request signal to be received from the main body control section 121. If the feeding request signal is received from the main body control section 121, in ACT 220, the CPU 130 waits for a predetermined time to elapse after the leading end of the preceding original document G turns on the pre-reading sensor 76. However, if the original document G1 is the first document (the preceding original document G is absent), the CPU 130 proceeds to ACT 221 without waiting for the predetermined time to elapse in ACT 220.

In ACT 221, the CPU 130 turns on the intermediate OUT motor 84 and the READ motor 87 and rotates the intermediate OUT rollers 18, the pre-reading rollers 50, the post-reading rollers 51, and the pre-paper discharge rollers 52 at speed conforming to an instruction of the main body control section 121.

In ACT 230, the CPU 130 waits for a fixed time to elapse. While waiting for the fixed time to elapse, the CPU 130 keeps the intermediate OUT motor 84 and the READ motor 87 on for the fixed time and continues to rotate the intermediate OUT rollers 18, the pre-reading rollers 50, the post-reading rollers 51, and the pre-paper discharge rollers 52 for the fixed time at speed conforming to an instruction of the main body control section 121. The intermediate OUT rollers 18, the pre-reading rollers 50, the post-reading rollers 51, and the pre-paper discharge rollers 52 continue to be rotated for the fixed time, whereby the original document G is fed a fixed distance. After keeping the intermediate OUT motor 84 and the READ motor 87 on for the fixed time, in ACT 231, the CPU 130 sends a reading start signal to the main body control section 121. The main body control section 121 receives the reading start signal and starts reading of an image on a front surface of the original document G1.

As shown in FIG. 12, the original document G1 travels on the READ document glass 110 a. The scanner 110 performs reading of an image of the original document G1.

After traveling on the READ document glass 110 a, the original document G1 is fed in the direction of the paper discharge rollers 53 through the post-reading rollers 51 and the pre-paper discharge rollers 52.

In ACT 232, the CPU 130 waits for the paper discharge sensor 78 to be turned on. Thereafter, if the leading end of the original document G1 reaches the paper discharge sensor 78, the paper discharge sensor 78 detects the original document G1 and is turned on. If the paper discharge sensor 78 is turned on, in ACT 233, the CPU 130 turns on the paper discharge motor 88 and rotates the paper discharge rollers 53. If duplex reading is performed, in ACT 237, the main body control section 121 starts reading of an image on a rear surface of the original document G1 with the CIS 60. After the paper discharge sensor 78 is turned on, in ACT 238, the main body control section 121 waits for a fixed time to elapse. After the fixed time elapses, in Act 241, the main body control section 121 ends the reading of the image on the surface of the original document G1 by the scanner 110. If the trailing end of the original document G1 passes through the post-reading rollers 51 and the reading sensor 77 is turned off, in ACT 242, the CPU 130 turns off the READ motor 87 and the intermediate OUT motor 84. If a predetermined time elapses after the reading sensor 77 is turned off, the main body control section 121 ends the reading of the image on the rear surface of the original document G1 by the CIS 60.

Thereafter, in ACT 260, the CPU 130 determines whether the original document G1 is the last original document (e.g., whether the empty sensor 70 is turned off after the original document G1 is fed). If the original document G1 is the last original document, the CPU 130 executes a paper discharge operation for the last original document. In other words, the CPU 130 performs an operation for turning off all the motors and the solenoids and ending an image reading and feeding control process for the original document G1. Specifically, in ACT 261, the CPU 130 waits for the paper discharge sensor 78 to be turned off. After the paper discharge sensor 78 is turned off, in ACT 262, the CPU 130 keeps the paper discharge motor 88 on for a fixed time and feeds the original document G1 a fixed distance. If the paper discharge motor 88 is kept on for the fixed time and the original document G1 is fed the fixed distance, in ACT 263, the CPU 130 turns off all the motors and the solenoids. Consequently, the control process for feeding the original documents and reading images is completed.

If the CPU 130 determines in ACT 260 that the original document G1 is not the last original document, the CPU 130 repeats the feeding of an original document by the OUT feeding section 26 and the IN feeding section 27 as explained below without carrying out the paper discharge operation. Specifically, first, if the registration sensor 71 is turned on by the first original document G1 in ACT 207, as interrupt processing, the CPU 130 starts feeding of a second original document G2 in parallel with and separately from the control process for the first original document G1. However, the second original document G2 is put on standby for a paper feeding process until the trailing end of the first original document G1 passes through the registration sensor 71. In ACT 300 and ACT 301, the CPU 130 waits for the trailing end of the first original document G1 to pass through the RGT sensor 71, whereby the RGT sensor 71 is turned off. If the RGT sensor 71 is turned off in ACT 300, in ACT 206, the CPU 130 turns on the pickup solenoid 81 and the paper feeding motor 80. The pickup solenoid 81 is turned on, whereby the pickup roller 12 descends and comes into contact with the original document G2 on the tray 11. The paper feeding motor 80 is turned on, whereby the pickup roller 12 rotates and starts feeding of the second original document G2 from the tray 11. Further, the paper feeding motor 80 is turned on, whereby the separating and feeding rollers 13 are rotated to feed the original document G2 fed from the tray 11.

If a leading end of the original document G2 reaches the position of the RGT sensor 71, in ACT 207, the RGT sensor 71 detects the original document G2 and is turned on. If the RGT sensor 71 is turned on, in ACT 208, the CPU 130 turns off the pickup solenoid 81 and the paper feeding motor 80 in a fixed time after the RGT sensor 71 is turned on. The original document G2 comes into contact with the registration rollers 14 and stops and the leading end of the original document G2 is aligned. In ACT 208, the CPU 130 turns off the gate solenoid 83 simultaneously with turning off the paper feeding motor 80. In ACT 211, the CPU 130 waits for a fixed time to elapse after the gate solenoid 83 is turned off. After the fixed time elapses, in ACT 212, the CPU 130 determines whether the original document G is an odd number-th original document or an even number-th original document. In this case, since the original document is the even number-th original document G2, in ACT 250, the CPU 130 turns on the gate solenoid 83. If the gate solenoid 83 is turned on, the gate 40 is switched to a direction in which the original document G2 is diverted to the IN feeding section 27.

In ACT 264, the CPU 130 checks whether the preceding first original document G1 is nipped by the pre-reading rollers 50, the leading end of the original document G1 reaches the position of the pre-reading sensor 76, and the pre-reading sensor 76 is on. If the pre-reading sensor 76 is on, the CPU 130 proceeds to ACT 251. If the pre-reading sensor 76 is on, in ACT 251, the CPU 130 turns on the RGT motor 82 and the intermediate IN motor 86 and rotates the registration rollers 14 and the intermediate IN rollers 28 at equal speed. If the RGT motor 82 and the intermediate IN motor 86 are turned on, as shown in FIG. 13, the second original document G2 is diverted to the gate 40 and travels to the IN feeding section 27. In other words, the original document G2 is put on standby until the preceding original document G1 enters between the pre-reading rollers 50. Thereafter, the original document G2 is fed to the IN feeding section 27 by the registration rollers 14 and the intermediate IN rollers 28 at timing when the preceding original document G1 enters between the pre-reading rollers 50.

In ACT 252 and ACT 254, the CPU 130 waits for the paper timing sensor IN 73 to be turned on. If the leading end of the second original document G2 reaches the position of the paper timing sensor IN 73, the paper timing sensor IN 73 is turned on. If the paper timing sensor IN 73 is turned on, in ACT 253, the CPU 130 turns off the RGT motor 82 and the intermediate IN motor 86 in a fixed time after the paper timing sensor IN 73 is turned off. The second original document G2 stops before the pre-reading rollers 50 in the IN feeding section 27. In ACT 256, the CPU 130 waits for a feeding request signal for the second original document G2 to be received from the main body control section 121. If the paper timing sensor IN 73 is not turned on even if the fixed time elapses in ACT 254, as explained above, the CPU 130 determines that the original document G1 caused a jam and informs the occurrence of the jam with the display unit or the like.

In ACT 257, the CPU 130 waits for a predetermined time to elapse after the pre-reading sensor 76 is turned on by the preceding original document G (the first original document G1). If the predetermined time elapses, in ACT 258, the CPU 130 turns on the intermediate IN motor 86 and the READ motor 87 and rotates the intermediate IN rollers 28, the pre-reading rollers 50, the post-reading rollers 51, and the pre-paper discharge rollers 52 at speed conforming to an instruction of the main body control section 121. Consequently, the CPU 130 matches timing when the trailing end of the preceding original document G (the first original document G1) passes the pre-reading rollers 50 and timing when the leading end of the second original document G2 starts to be fed by the pre-reading rollers 50. As shown in FIG. 14, the second original document G2 is fed to the READ document glass 110 a in a state in which a distance between a trailing end α1 of the preceding original document G (the first original document G1) and a leading end β1 of the second original document G2 is reduced to near 0 mm.

In order to reduce and/or minimize the distance between the trailing end α1 of the preceding original document G (the first original document G1) and the leading end β1 of the second original document G2 to near 0 mm, a distance from the paper timing sensor OUT 72 to the pre-reading rollers 50 and a distance from the paper timing sensor IN 73 to the pre-reading rollers 50 are set to an equal distance. As shown in FIG. 15, the second original document G2 is put on standby in a position a fixed distance γ1 ahead after the paper timing sensor IN 73 is turned on. If the trailing end of the preceding original document G (the first original document G1) passes through the paper timing sensor OUT 72 and moves forward the fixed distance γ1, the CPU 130 turns on the READ motor 87 and the intermediate IN motor 86 and feeds the second original document G2 in the direction of the READ document glass 110 a. This makes it possible to reduce and minimize the distance between the trailing end of the first original document G1 and the leading end of the second original document G2 to near 0 mm.

Alternatively, according to a detection result of the paper timing sensor OUT 72 and a detection result of the paper timing sensor IN 73, feeding timing of the preceding original document G (the first original document G1) and the second original document G2 may be adjusted in advance to reduce the distance between the preceding original document G (the first original document G1) and the second original document G2 to near 0 mm.

If the second original document G2 is fed to the READ document glass 110 a following the preceding original document G (the first original document G1) in ACT 258, in ACT 230, the main body control section 121 waits for a fixed time to elapse. If the fixed time elapses, whereby the original document G2 is fed a fixed distance, in Act 231, the main body control section 121 starts reading of an image on a front surface of the original document G2 by the scanner 110.

Thereafter, in ACT 232, the CPU 130 waits for the paper discharge sensor 78 to be turned on. If the leading end of the original document G2 reaches the position of the paper discharge sensor 78 and the paper discharge sensor 78 is turned on, in ACT 233, the CPU 130 turns on the paper discharge motor 88 and rotates the paper discharge rollers 53. If duplex reading is performed, in Act 237, the main body control section 121 starts reading of an image on a rear surface of the original document G2 with the CIS 60. After the paper discharge sensor 78 is turned on, in ACT 238, the main body control section 121 waits for a fixed time to elapse. After the fixed time elapses, in ACT 241, the main body control section 121 ends the reading of the image on the front surface of the original document G1 by the scanner 110. If a trailing end of the original document G2 passes through the post-reading rollers 51 and the reading sensor 77 is turned off, in ACT 242, the CPU 130 turns off the READ motor 87 and the intermediate OUT motor 84. If a predetermined time elapses after the reading sensor 77 is turned off, the main body control section 121 ends the reading of the image on the rear surface of the original document G2 by the CIS 60.

Thereafter, in ACT 260, the CPU 130 determines whether the original document G2 is the last original document. If the original document G2 is the last original document (e.g., if the empty sensor 70 is turned off after the original document G2 is fed), the CPU 130 executes an operation for discharging the last original document. In other words, the CPU 130 performs an operation for turning off all the motors and the solenoids and ending the image reading and feeding control process for the original document G2. Specifically, in ACT 261, the CPU 130 waits for the paper discharge sensor 78 to be turned off. After the paper discharge sensor 78 is turned off, the CPU 130 keeps the paper discharge motor 88 on for a fixed time and feeds the original document G2 a fixed distance. If the paper discharge motor 88 is kept on for the fixed time and the original document G2 is fed the fixed distance, in ACT 263, the CPU 130 turns off all the motors and the solenoids. Consequently, the control process for feeding the two original documents G is completed.

A control process for feeding a third original document G3 and reading an image is explained. If the CPU 130 determines in Act 260 that the original document G2 is not the last original document, the CPU 130 performs a control process for the third original document G3 explained below without carrying out the ending operation explained above. First, if the registration sensor 71 is turned on by the second original document G2 in ACT 207, as interrupt processing, the CPU 130 starts feeding of the third original document G3 in parallel with and separately from the control process for the second original document G2. However, the third original document G3 is put on standby for a paper feeding process until the trailing end of the last sheet of the second original document G2 passes through the registration sensor 71. In ACT 300 and ACT 301, the CPU 130 waits for the trailing end of the last sheet of the preceding second original document G2 to pass through the RGT sensor 71, whereby the RGT sensor 71 is turned off. If the RGT sensor 71 is turned off in ACT 300, in ACT 206, the CPU 130 turns on the pickup solenoid 81 and the paper feeding motor 80. The pickup solenoid 81 is turned on, whereby the pickup roller 12 descends and comes into contact with the original document G3 on the tray 11. The paper feeding motor 80 is turned on, whereby the pickup roller 12 rotates and starts feeding of the third original document G3 from the tray 11. Further, the paper feeding motor 80 is turned on, whereby the separating and feeding rollers 13 are rotated to feed the original document G3 fed from the tray 11.

Thereafter, in ACT 207, the CPU 130 waits for the RGT sensor 71 to detect the original document G3 to be turned on. If a leading end of the original document G3 reaches the position of the RGT sensor 71, the RGT sensor 71 detects the original document G3 and is turned on. If the RGT sensor 71 is turned on, in ACT 208, the CPU 130 turns off the pickup solenoid 81 and the paper feeding motor 80 in a fixed time after the RGT sensor 71 is turned on. The original document G3 comes into contact with the registration rollers 14 and stops and the leading end of the original document G3 is aligned. If the gate solenoid 83 is turned off, the gate 40 is switched to a direction in which the original document G3 is diverted to the OUT feeding section 26. Thereafter, in ACT 211, the CPU 130 waits for a fixed time to elapse. After the fixed time elapses, in ACT 212, the CPU 130 determines whether the original document G is an odd number-th original document or an even number-th original document.

In ACT 265, the CPU 130 checks whether the preceding first original document G1 is nipped by the pre-reading rollers 50, the leading end of the original document G1 reaches the position of the pre-reading sensor 76, and the pre-reading sensor 76 is on. If the pre-reading sensor 76 is on, the CPU 130 proceeds to ACT 251.

In this case, since the original document G is the third original document G3, in ACT 265, the CPU 130 checks whether the preceding second original document G2 is nipped by the pre-reading rollers 50, the leading end of the original document G2 reaches the position of the pre-reading sensor 76, and the pre-reading sensor 76 is on. If the pre-reading sensor 76 is turned on, the CPU 130 proceeds to ACT 214. If the pre-reading sensor 76 is on, in ACT 214, the CPU 130 turns on the RGT motor 82 and the intermediate OUT motor 84 and rotates the registration rollers 14 and the intermediate OUT rollers 18 at equal speed. If the RGT motor 82 and the intermediate OUT motor 84 are turned on, the third original document G3 is diverted to the gate 40 and moves forward to the OUT feeding section 26. Specifically, the original document G3 is put on standby until the preceding original document G2 enters between the pre-reading rollers 50. Thereafter, the original document G3 is fed to the OUT feeding section 26 by the registration rollers 14 and the intermediate OUT rollers 18 at timing when the preceding original document G2 enters between the pre-reading rollers 50. In ACT 215, the CPU 130 waits for the paper timing sensor OUT 72 to be turned on. If the original document G3 reaches the position of the paper timing sensor OUT 72 and the paper timing sensor OUT 72 is turned on, in ACT 216, after keeping the RGT motor 82 and the intermediate OUT motor 84 on for a fixed time, the CPU 130 turns off the RGT motor 82 and the intermediate OUT motor 84.

As shown in FIG. 17, the first original document G1 is placed on the paper discharge tray 56, the second original document G2 travels on the READ document glass 110 a and turns on the paper discharge sensor 78, and the third original document G3 stops before the pre-reading rollers 50 in the

OUT feeding section 26. Thereafter, in ACT 218, the CPU 130 waits for a feeding request signal for the third original document G3 to be received from the main body control section 121. If, in ACT 217, the paper timing sensor OUT 72 is not turned on even if the fixed time elapses, as explained above, the CPU 130 determines that the original document G caused a jam.

In ACT 220, the CPU 130 waits for a predetermined time to elapse after the pre-reading sensor 76 is turned on by the preceding original document G (the second original document G2). If the predetermined time elapses, in ACT 221, the CPU 130 turns on the intermediate OUT motor 84 and the READ motor 87 and rotates the intermediate OUT rollers 18, the pre-reading rollers 50, the post-reading rollers 51, and the pre-paper discharge rollers 52 at speed conforming to an instruction of the main body control section 121. Consequently, the CPU 130 matches timing when the trailing end of the preceding original document G (the second original document G2) passes the pre-reading rollers 50 and timing when the leading end of the third original document G3 starts to be fed by the pre-reading rollers 50. As shown in FIG. 14, the third original document G3 is fed to the READ document glass 110 a in a state in which a distance between a trailing end α1 of the preceding original document G (the second original document G2) and a leading end □1 of the third original document G3 is reduced to near 0 mm.

In order to reduce and/or minimize the distance between the trailing end α1 of the preceding original document G (the second original document G2) and the leading end β1 of the third original document G3 to near 0 mm, the distance from the paper timing sensor OUT 72 to the pre-reading rollers 50 and the distance from the paper timing sensor IN 73 to the pre-reading rollers 50 are set to the equal distance as explained above. As shown in FIG. 15, the third original document G3 is put on standby in the position the fixed distance γ1 ahead after the paper timing sensor OUT 72 is turned on. If the trailing end of the preceding original document G (the second original document G2) passes through the paper timing sensor IN 73 and moves forward the fixed distance γ1, the CPU 130 turns on the READ motor 87 and the intermediate OUT motor 84 and feeds the third original document G3 in the direction of the READ document glass 110 a. This makes it possible to reduce the distance between the trailing end of the second original document G2 and the leading end of the third original document G3 to near 0 mm.

Alternatively, according to a detection result of the paper timing sensor IN 73 and a detection result of the paper timing sensor OUT 72, feeding timing of the preceding original document G (the second original document G2) and the third original document G3 can be adjusted in advance to reduce the distance between the preceding original document G (the second original document G2) and the third original document G3 to near 0 mm.

If the third original document G3 is fed to the READ document glass 110 a following the preceding original document G (the second original document G2) in ACT 221, in ACT 230, the main body control section 121 waits for a fixed time to elapse. If the fixed time elapses, whereby the original document G3 is fed a fixed distance, in Act 231, the main body control section 121 starts reading of an image on a front surface of the original document G3 by the scanner 110.

Thereafter, in ACT 232, the CPU 130 waits for the paper discharge sensor 78 to be turned on. If the leading end of the original document G3 reaches the position of the paper discharge sensor 78 and the paper discharge sensor 78 is turned on, in ACT 233, the CPU 130 turns on the paper discharge motor 88 and rotates the paper discharge rollers 53. If duplex reading is performed, in Act 237, the main body control section 121 starts reading of an image on a rear surface of the original document G3 with the CIS 60. After the paper discharge sensor 78 is turned on, in ACT 238, the main body control section 121 waits for a fixed time to elapse. After the fixed time elapses, in ACT 241, the main body control section 121 ends the reading of the image on the front surface of the original document G3 by the scanner 110. If a trailing end of the original document G3 passes through the post-reading rollers 51 and the reading sensor 77 is turned off, in ACT 242, the CPU 130 turns off the READ motor 87 and the intermediate OUT motor 84. If a predetermined time elapses after the reading sensor 77 is turned off, the main body control section 121 ends the reading of the image on the rear surface of the original document G3 by the CIS 60.

Thereafter, in ACT 260, the CPU 130 determines whether the original document G2 is the last original document. If the original document G2 is the last original document (e.g., if the empty sensor 70 is turned off after the original document G2 is fed), the CPU 130 performs an operation for turning off all the motors and the solenoids and ending the image reading and feeding control process for the original document G2. Specifically, in ACT 261, the CPU 130 waits for the paper discharge sensor 78 to be turned off. After the paper discharge sensor 78 is turned off, the CPU 130 keeps the paper discharge motor 88 on for a fixed time and feeds the original document G2 a fixed distance. If the paper discharge motor 88 is kept on for the fixed time and the original document G2 is fed the fixed distance, in ACT 263, the CPU 130 turns off all the motors and the solenoids. Consequently, the control process for feeding the two original documents G is completed.

Thereafter, in ACT 260, the CPU 130 determines whether the original document G1 is the last original document (e.g., whether the empty sensor 70 is turned off after the original document G1 is fed). If the original document G1 is the last original document, the CPU 130 executes a paper discharge operation for the last original document.

Thereafter, in ACT 260, the CPU 130 determines whether the original document G3 is the last original document. If the original document G3 is the last original document (e.g., if the empty sensor 70 is turned off after the original document G3 is fed), the CPU 130 executes a paper discharge operation for the last original document. In other words, the CPU 130 performs an operation for turning off all the motors and the solenoids and ending the image reading and feeding control process for the original document G3. Specifically, in ACT 261, the CPU 130 waits for the paper discharge sensor 78 to be turned off. After the paper discharge sensor 78 is turned off, the CPU 130 keeps the paper discharge motor 88 on for a fixed time and feeds the original document G3 a fixed distance. If the paper discharge motor 88 is kept on for the fixed time and the original document G3 is fed the fixed distance, in ACT 263, the CPU 130 turns off all the motors and the solenoids. Consequently, the control process for feeding the three original documents G and reading images is completed. If the CPU 130 determines in ACT 260 that the original document G is not the last original document, the CPU 130 executes the image reading control process for the original document G2 concerning the even number-th original document G and executes the image reading control process for the second original document G3 concerning the odd number-th original document G without executing the paper discharge operation.

According to this embodiment, when the original documents G are continuously read, the two feeding sections: the OUT feeding section 26 and the IN feeding section 27 are used. While the preceding original document G1 is fed using one feeding section, the following original document G2 is fed into the other feeding section and put on standby in the other feeding section. The feeding of the following original document G2 into the other feeding section is performed at timing when the preceding original document G1 enters between the pre-reading rollers 50 provided before the reading sensor 77 (the scanner 110). Therefore, when the following original document G2 is on standby in the other feeding section, the preceding original document G1 is typically nipped by the pre-reading rollers 50. Therefore, even if a jam of the preceding original document G1 occurs in a state in which the preceding original document G1 and the next original document G2 are present in the OUT feeding section 26 and the IN feeding section 27, the user can determine which of the two original documents remaining in the feeding sections is the preceding original document G (nipped by the pre-reading rollers 50) and which is the following original document G (not nipped by the pre-reading rollers 50) and can return the two original documents remaining in the feeding sections to the tray 11 in correct order.

Moreover, timing when the preceding original document G1 passes through the scanner 110 and timing when the next original document G2 is fed to the scanner 110 are matched to continuously feed the original documents G in a state in which a distance between the preceding original document G1 and the next original document G2 is reduced to near 0 mm.

Even if feeding speed for the original document G is not increased, it is possible to improve feeding properties for the original document G by the ADF 10 and improve image reading speed by the scanner 110 and productivity of an image forming apparatus including the scanner 110. Moreover, it is possible to prevent damage to the original document G that occurs if the feeding speed is increased or suppress noise that occurs if the feeding speed is increased.

The several embodiments are explained above. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be carried out in other various forms. Various omissions, substitutions, and changes of the embodiments are possible without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention and are included in the inventions described in claims and the scope of equivalents of the inventions. 

1. An auto-document feeder comprising: a paper feeding section configured to feed sheets of an original document one by one, from which images are read by an image reading section; a first feeding section configured to feed the original document, which is fed by the paper feeding section, in a direction of the image reading section through a first feeding path; a second feeding section configured to feed a different sheet of the original document, which is fed by the paper feeding section, in the direction of the image reading section through a second feeding path different from the first feeding path; a third feeding section configured to alternately nip one by one the original documents fed by the first feeding section and the second feeding section and feed the original documents to the image reading section; a determining section configured to determine that the original document is nipped by the third feeding section; and a document diverting and feeding section configured to alternately divert and feed the original documents, which are fed by the paper feeding section, into the first feeding path and the second feeding path and, if a preceding original document is present, after the preceding original document is detected by the determining section, feed a following original document into the first or second feeding path into which the preceding original document is not fed.
 2. The feeder according to claim 1, wherein the third feeding section includes a pair of feeding rollers and alternately nips one by one, between the feeding rollers, the original documents fed by the first feeding section and the second feeding section and feeds the original documents to the image reading section.
 3. The feeder according to claim 2, wherein, a sensor provided between the feeding rollers and the image reading section detects the original document fed by the feeding rollers, whereby the determining section determines that the original document is nipped by the third feeding section.
 4. The feeder according to claim 3, wherein the document diverting and feeding section includes registration rollers configured to align leading ends of the original documents fed by the paper feeding section and feed the original documents into the first feeding path and the second feeding path, and if the preceding original document is present, after the preceding original document is detected by the determining section, the registration rollers feed a following document into the first feeding path or the second feeding path.
 5. The feeder according to claim 4; wherein the document diverting and feeding section includes a gate configured to alternately divert the original documents, which are fed by the registration rollers, to the first feeding path and the second feeding path.
 6. The feeder according to claim 5, wherein the paper feeding section includes: a tray on which plural original documents are stacked; a pickup roller configured to pick up the original documents stacked on the tray; and separating rollers configured to separate and feed the original documents one by one picked up by the pickup roller.
 7. The feeder according to claim 6, wherein the document diverting and feeding section includes a second detecting section provided between the registration rollers and the separating rollers and configured to detect that the original document fed by the separating rollers reaches the registration rollers and passes the registration rollers, and the pickup roller and the separating rollers start feeding of the following original document after the second detecting section detects that the preceding original document passes the registration rollers.
 8. The feeder according to claim 1, wherein the first feeding section includes first intermediate feeding rollers along the first feeding path, the second feeding section includes second intermediate feeding rollers along the second feeding path, and the first intermediate feeding rollers and the second intermediate feeding rollers feed the original document, which is fed from the first feeding path or the second feeding path, to the image reading section in cooperation with the third feeding section.
 9. The feeder according to claim 8, wherein, if the preceding original document is present in one of the first feeding path or the second feeding path, the first intermediate feeding rollers and the second intermediate feeding rollers feed, after putting the following original document present in the other feeding path on standby, a following original document.
 10. An image reading apparatus comprising: an image reading section configured to read an image of an original document; a paper feeding section configured to feed the original documents one by one, from which the images are read by the image reading section; a first feeding section configured to feed the original document, which is fed by the paper feeding section, in a direction of the image reading section through a first feeding path; a second feeding section configured to feed the original document, which is fed by the paper feeding section, in the direction of the image reading section through a second feeding path different from the first feeding path; a third feeding section configured to alternately nip one by one the original documents fed by the first feeding section and the second feeding section and feed the original documents to the image reading section; a detecting section configured to detect that the original document is nipped by the third feeding section; and a document diverting and feeding section configured to alternately divert and feed the original documents, which are fed by the paper feeding section, into the first feeding path and the second feeding path and, if a preceding original document is present, after the preceding original document is detected by the detecting section, feed a following original document into the first or second feeding path into which the preceding original document is not fed. 